Printing-plate.



L. B. TEBBETTS, 2D.

PRINTING PLATE. APPLICATION FILED JULY 1 191! Patented Feb. 17, 1914.

TIN 60% T0 90% ANTLMQNY 3% T0 8% /{LEAD 5% T0 50% Mbasls TIN 0% TO L976 mvantor'.

LEWIS B. TEBBETTS, 213, OF ST. LOUIS, MISSOURI.

PRINTING-PLATE.

To all whom it may conc ern Be it known that 1, Lewis B. TEBBn'rTs, 2d, a citizen of the United States of America, residing in the city of St. Louis and State of Missouri, have invented certain new and useful Improvements in Printingllates, of which the following is a full, clear, and exact description.

My invention relates to a printing plate, and it has for its object the roduction of a metal plate of this kind, ess expensive than metal plates heretofore made for the same purpose. I

With this object in view, the improvement contemplates a multiple ply metal printing plate comprising a facing layer of an alloy of metals which may be readily and efii-' ciently cut by engraving tools to produce a highly satisfactory printing surface and a metal backing layer for such facing layer that is of less expensive'nature than the facing layer, but is capable of performing all of the service required at the back of the engraved portion of the plate, such as the furnishing of the necessary stability, rigidity and stiffness in the plate.

Manufacturers of metal printing plates,

such as are intended to be prepared y engraving, have for many years endeavored to produce a satisfactory metal printin plate :composition consisting of lead and antimony, but it has been found that when sufficient antimony was included in the composition to render the plates of the desired stiffness, the metal was so brittle as to make it impossible to cut clear, sharp, and well defined lines in engraving operations.

By my improvement, I produce a metal printing plate facing surface embodying the materlals mentioned, and which is exactly suited to the' engravers needs, this improvement contemplating the employment of another component part of an alloy, namely: tin, which enters into the composition as the main element, is hardened by the presence of antimony, and. the alloy, which would otherwise be too stiff and brittle is softened by the-"addition of a comparatively small percentage of lead relative to the percentage of tin to render the alloy more ductile than it, would be if composed of only tin and antimony.

'In order that my invention may be more fully understood I will proceed to describe it with reference to the accompanying drawing which is an edge view of my improved Specification of Letters Patent.

plate showing the layers thereof marked ,with their constituent elements.

The facing layer of my printing plate, as

most commonly made, is composed of tin, antimony and lead, these elements being used in the following proprtions to-wit: tin, from to 90%; antimony, from 2% to 8%, and lead, from 5% to 30%. In this composition, the tin being of a tough nature and being the principal component in the composition serves to render the facing of the platetough in nature, the antimony serves as a hardenin and stiffening agent, and the lead as a softening agent. By the combination of these elements, I produce a printing plate facin layer having all the essential characteristics necessary to permit the production of clear, sharp, and well defined lines when engraving operations are carried out in such layer, inasmuch as the characteristic toughness of the tin compensates for the brittleness of the antimony, thev antimony affords the required hardness and stiffness, and the lead in a minor proportion relative to the tin renders the alloy softer and more ductile so that it may be satisfactorily worked in the operations necessary in engraving a printing plate.

The presence of lead in the facing composition is more particularly desirable in producing a printing plate for use in engraving music printing plates, inasmuch as it is common practicein engraving such plates to stamp the note characters by the use of dies, as distinguished from engraving or cutting the othercharacters and lines; and it is necessary after the stamping operations to partially return the stamped portions of thep ate by pressure exerted at the back of the plate,

this pressure being usually applied by hammer blows against the body of the plates, In this connection, it is important that the facing layer of the plate be soft or ductile hence, the desirability of using lead to furnish softness and ductility in the printing plate facing layer.

The facing layer of my rinting plate is laid upon and securely attac ed to a backing layer composed of lead, antimony and tin, these elements bein used in the following proportions,-to wit: ead, 80% to 97%; antimony, 1% to 15%; tin, 0% to 19%. In this backing layer composition, lead predominates as the main element, being used as such main element princi ally by reason of its being less expensive t an the other ele- Patented Feb. 1%, 1914 7 Application filed July 1, 1911. Serial No. 636,518.

ments; the antimony is used to stifi'en the composition, and the tin to toughen the composition. Neither of the last named elements would be satisfactory if used alone With the lead, for the reason that while the antimony would aiford thenecessar stiffness in the backing layer, its resence a one with the lead would maket e composition too brittle; While the tin, if used alone with the lead, would render the composition tough, but would not afford the necessary stiifness. The importance of usin the three elementslead, antimony, anfi tin in the backing layer is, therefore, apparent.

While I have herein described my im provement as relating particularly to a printing plate, there may be other uses for a plate made in accordance with my invention; and I, therefore, do not desire to be limited to its use for any specific purpose.

I claim L In a metal plate, a facin layer comprising an alloy of tin, a sti ening agent,

and a softening agent, the percentage of tin being in excess of the other components in said facing layer; and a backin layer comprising an allo of lead, a sti ening agent and a toughening agent, the percentage of lead in said backing layer being in excess of the percentages of the other components in said layer.

2. In a-metal plate, a facing layer comprising an alloy of tin, antimony and lead, the percentage of tin in said facing layer being in excess of the antimony and lead alloy of lead, antimony and tin, the percentage of lead in said backing layer being in excess of the antimony and tin therein.

3. In a metal plate, a facing layer comprising a facing of alloy of from sixty per cent. to ninety per cent. of tin, from tWo per cent. to eightper cent. of antimony, and of five per cent. to thirty per cent. of lead; and a backing layer comprising lead, a stiffening agent and a toughening agent, the. percentage of lead in said backing layer being in excess of the other components in said backing layer.

4:- In a metal plate, a facing layer comprising an alloy of from sixty per cent. to ninety per cent. of tin, from two er cent. to'eight' per cent. of antimony, and cm five per cent. to thirty per cent. of lead; and a backing layer comprising an alloy of from eight per cent. to ninety per cent. of lead, a sti ening agent and a toughening agent.

5. In a metal plate, a facing layer comprising an alloy of from sixty per cent. to ninety per cent. of tin, from two per cent. to eight per cent. of antimony, and of five per cent. to thirty per cent. of lead, and a backing layer comprising an alloy of from eighty per cent. to ninety-seven per cent. of lead, and the balance of antimony and tin.

LEWIS B. TEBBETTIS, 2D. 

